Fact check: Who has a say in sending Australian troops to war?

"The Australian people, through the entire Australian Parliament, deserve a say in whether we go to war but Tony Abbott, Clive Palmer and the Labor party disagree," Greens Leader Christine Milne said on September 4.

As Australia's involvement in the Middle East conflict against the Islamic State deepens, the Greens want that involvement debated and approved by Parliament.

On September 1, as the Greens signalled they would push for full parliamentary debate - and a vote - about the military deployment, Foreign Minister Julie Bishop told ABC Radio that the Coalition Government would continue to exercise the power to unilaterally make decisions about sending troops overseas.

"We will adopt the usual convention of past governments and that is that the government of the day has the ultimate responsibility for making decisions involving our military," Ms Bishop said.

"There is an opportunity to debate the issue in the Parliament, but governments of both sides have always adopted a convention of making the decisions in relation to military activity - I'm thinking of the Hawke government in the original Gulf War - so we will do what has always been done."

The claim: Julie Bishop says the government of the day has the ultimate responsibility for making decisions involving Australia's military.

The verdict: Since federation in 1901, and for all conflicts since World War I, the Prime Minister and Cabinet have made all decisions about deploying troops.

So what has "always been done?" ABC Fact Check takes a look at how past governments have decided to deploy troops overseas.

The World Wars

WWI 1914

Neither Australia or any of the other Commonwealth dominions was consulted before Britain declared war on August 4, 1914, following the assassination of Archduke Franz Ferdinand on June 28.

Even if Australia had been consulted, parliament was not sitting to debate the issue, having been suspended ahead of a July federal election.

Because Britain had made the decision, the Australian government's role was strictly limited to deciding the extent of its military contribution to the war effort, even though, as historian C.E.W. Bean wrote, Cabinet had already decided in principle to commit troops before war was officially declared.

Labor opposition leader Andrew Fisher said during an election campaign speech in Colac on July 31, that "should the worst happen, after everything has been done that honour will permit, Australians will stand beside the mother country to help and defend her to our last man and our last shilling".

The question of whether to support Britain was decided in the affirmative, without division, in both Houses.

WWII 1939

In September 1939, prime minister Robert Menzies announced it was his "melancholy duty" to officially confirm that "Great Britain has declared war upon [Germany] and that, as a result, Australia is also at war".

The first Australian troops deployed were air force personnel already stationed in Britain, in October 1939.

A federal election in September 1940 left the ALP and Coalition with the same number of seats in the House of Representatives. Two Victorian independents held the balance of power, while government held power in the Senate 19 seats to 17 ALP seats.

While troops had already been deployed, and ALP leader John Curtin supported the war effort in principle, he refused to join his foe, Menzies to form a majority government and used his power in the House of Representatives to force Menzies to establish an Advisory War Council with members from both the government and the opposition.

When Curtin won power in October 1941, he moved that parliament "approve the action" in concurrence with the war council of declaring Australia at war with countries including Japan, Finland, Hungary and Romania and Bulgaria. It was approved without division.

It called for all member states to fight against those governments, and Australia's executive government made a decision to take part in both, before any parliamentary debate.

In July 1950, Liberal prime minister Robert Menzies moved that "This House... approves of the action taken by the Government in placing at the disposal of the United Nations the forces indicated in the statement of the Prime Minister".

The motion was not opposed in the House of Representative, but the Senate Opposition leader William Ashley noted: "Whilst it is not always opportune to call the Parliament together and it is realised that certain matters must be dealt with urgently, I stress that any future Australian commitments should have the approval of Parliament." Menzies' motion was approved without division in both Houses.

In December 1990, three and a half months after officially condemning the Iraqi invasion of Kuwait, Labor prime minister Bob Hawke told parliament that the government "unreservedly supports" a UN resolution imposing a January 15 deadline on Iraq to withdraw from Kuwait and authorising action if it did not. "Our support for the resolution imposes on us an obligation to respond to the request... for all nations to provide appropriate support for actions taken under the resolution," Mr Hawke said. His motion was unopposed.

On January 21, 1991, two days after full scale war had erupted in Iraq, Hawke recalled Parliament for 48 hours. There was no question time scheduled. Hawke stated: "The decision to commit Australian armed forces to combat is of course one that constitutionally is the prerogative of the executive. It is fitting, however, that I place on parliamentary record the train of events behind this decision", before moving a motion for the House of Representatives to reaffirm its support for Australia's role.

The motion was passed without division, although Independent member for North Sydney, Ted Mack, recorded his opposition to the motion.

It was passed in the Senate 59 votes to nine.

The Malayan emergency, 1951 and Indonesia confrontation, 1963

A deteriorating security situation between the Malayan Communist Party and the British colonial government in Malaya, which the MCP referred to as the 'Anti-British National Liberation War', began in 1948.

Liberal prime minister Robert Menzies formally told parliament in late May 1950 of his decision to "render aid" by providing aircraft and crews in response to a British request. His motion that the "papers be printed" was passed in July by both houses without division, a formality recognising that a decision had been made by government.

The Coalition government issued a press release in May 1962 stating that the Republic of Vietnam had asked Australia to send military instructors, and it was agreeing to that request. Parliament was adjourned at the time, so there was no debate.

"On 10 November 1964 Liberal prime minister Robert Menzies announced the introduction of a new scheme for peacetime conscription by which 20-year-old males were chosen by a ballot of birth dates to serve for two years in the Australian Army. This included overseas service," a government history states.

On December 4, 1964, the US requested Australia deploy combat troops.

In late April 1965 Menzies told parliament: "We have decided in principle some time ago... that we would be willing to [provide an infantry battalion] if we received the necessary request."

During debate, the Opposition recorded its "complete" resistance to the decision. Parliament was asked to vote on a motion "that the paper be printed". It passed 60 votes to 44 in the House of Representatives and without a division in the Senate.

Afghanistan 2001

On October 4, 2001 Liberal prime minister John Howard held a press conference confirming that Australia would commit military assets, including special forces and air to air refuelling aircraft, to support the US mission in Afghanistan. Mr Howard earlier told opposition leader Kim Beazley of the decision.

No statement about the deployment of troops was made in parliament, although parliament had already supported Howard's decision to invoke the ANZUS Treaty to signal Australia's support for the US following the September 11 terrorist attacks.

Second Gulf War 2003

Australia's decision to join the US-led "coalition of the willing" to invade Iraq in search of weapons of mass destruction triggered some of the most rigorous objections from within parliament in history.

In January 2002 US president George W Bush declared Iraq to be part of "an axis of evil". In October 2002, the US government authorised the use of military force against Iraq. Prime minister John Howard had already indicated he would consider any request for Australian involvement in Iraq. "We are not automatically committed in advance to be involved in any operation the Americans undertake but if they do ask for our involvement we'll look it at and we'll look at it very sympathetically and consistently with the willingness that we have shown in the past to align ourselves where we believe what they are doing is not only just but also in Australia's national interests," Mr Howard said at a London press conference in March 2002.

On September 17, 2002 foreign affairs minister Alexander Downer put a statement to the parliament for debate, the first public debate about Australia's possible role in a second Iraq war.

A week later, the Australian Democrats unsuccessfully called for a conscience vote on potential troop deployment.

On January 22, 2003 defence minister Robert Hill held a press conference confirming Australia would send troops to Iraq, as had been foreshadowed by Mr Howard earlier that month.

On March 18, President Bush gave a speech indicating America would fight to remove Iraqi president Saddam Hussein after Congress approved military action in Iraq. On the same day a motion was put before the House of Representatives requesting that it endorse the government's decision to commit troops to the international coalition, with the prime minister telling parliament that he believed Iraq possessed weapons of mass destruction.

Labor opposition leader Simon Crean said: "Labor opposes your commitment to war. We will argue against it and we will call for the troops to be returned."

The motion was supported in the House of Representatives two days later, 80 votes to 63.

Does the Prime Minister have the final say?

Ms Bishop says the government of the day has "ultimate responsibility" for decisions about Australia's military.

Australia's constitution vests the power of decision making with the Queen, in conference with the Governor-General. It is generally accepted that the Governor-General acts on the advice of the Prime Minister and the Federal Executive Council, comprised of all ministers and parliamentary secretaries.

This applies to decision making "for the execution and maintenance" of the Constitution and the laws of the Commonwealth, otherwise known as the "executive power" provision.

The extent to which the executive government can legally exercise its powers independent of Parliament continues to be the subject of significant debate. In relation to decisions about the military, it is generally acknowledged that the government has the power to declare war and deploy troops overseas, because of the executive power provision.

The executive government's power can be limited or regulated by Parliament, in certain areas which are set out in the Constitution under the "legislative powers" provision.

Legal expertshave suggested Parliament may have the right to limit the executive's decision making capability for areas such as defence, because Parliament is specifically given the power to make laws with respect to the "naval and military defence of the Commonwealth... and the control of the forces".

Senate attempts to authorise troop deployment

On September 4, Greens Leader Christine Milne asked the Senate to pass a bill giving Parliament the power to decide questions about how and when to deploy troops. The attempt was defeated 54 votes to 12 - with only the Greens and Senators Nick Xenophon and David Leyonhjelm voting yes.

Senator Milne was not the first parliamentarian to argue for parliamentary oversight of major military decisions.

In 1985 Australian Democrats senator Colin Mason introduced a bill seeking to guarantee parliamentary approval before Australian troops were deployed overseas. Democrat Senator Paul McLean introduced the same bill in 1988.

In 2003, Democrat senators Andrew Bartlett and Natasha Stott-Despoja introduced a Bill with a similar purpose. Senator Bartlett tried again in 2008, while Greens Senator Scott Ludlam also tried the same year.

All these attempts failed.

A research note published by the Parliamentary Library in 2010 said parliament had never legislated to ensure that all major decisions regarding Australia's commitment to a war are first approved by both the House of Representatives and the Senate, rather than just the executive government.

The verdict

In most cases, the decision to deploy Australian troops overseas has been bipartisan.

No parliament has ever been given the opportunity to debate Australia's active role in a foreign conflict before the Prime Minister of the day has made a decision about committing to military engagement.

Since Federation in 1901, and for all conflicts since World War I, the Prime Minister and Cabinet have made all decisions about deploying troops.